The relative concentration, stability and structural diversity of metabolites in biological samples present challenges in systems biology and in diagnostic medicine when the goal is to analyze several (e.g., dozens or hundreds) of metabolites that can vary in chemical structure (e.g., aminos, ketones, carboxylic acids). Typically, a specific reagent is used to derivatize one structural class of metabolites for each analysis. This “one reagent-one functional group” method can be technically cumbersome when analyzing metabolites of varying structures in a biological sample. Thus, there is a need to develop new methods to analyze metabolites of varying chemical structure in a sample.